The invention relates to a heat exchanger, in particular a heat exchanger for a heating or air-conditioning system for motor vehicles in which a gaseous refrigerant is cooled by heat exchange contact with ambient air.
EP 0 845 648 A2 discloses a flat-tube heat exchanger, in particular a condenser of the serpentine type, with a flat-tube block consisting of one or more flat tubes which issue with preferably twisted end portions on the opposite or on the same tube block side into respective connection-space components, that is to say header tubes, so that, should the header tubes be arranged on the same tube block side, two header tubes running adjacently and parallel to one another are provided. In this case, a plurality of serpentine-shaped flat tubes may be provided, in which adjacent flat tubes are arranged with their inlet-side or their outlet-side tube portions adjacent to one another in the longitudinal direction of the header tubes, the serpentines comprising a plurality of 180° bends. A corresponding arrangement prevents heat transmission losses, but still leaves much to be desired.
EP 0 414 433 discloses a duplex heat exchanger which allows a coolant throughflow in cross countercurrent, in that two flat heat exchangers arranged one behind the other, designated hereafter as blocks, in each case with two header tubes which are connected to one another via a multiplicity of flat tubes, are provided. The two blocks are connected to one another by means of flanges and O-ring seals, for which purpose they have to be constructed, tensioned and soldered separately and, after soldering, connected to one another. The supply of the coolant to the block through which the flow passes first takes place in an upper region, the outlet at the bottom, and, in the second block through which the flow subsequently passes, inlet can take place both at the bottom and at the top, and outlet takes place correspondingly at the top or at the bottom. A duplex heat exchanger of this type which consists of two blocks entails a multiplicity of individual parts and a relatively high outlay in production terms, so that production is costly. Furthermore, a heat exchanger of this type still leaves much to be desired with regard to thermal properties.
Moreover, DE 100 43 439 A1 discloses a radiator for a supercritical steam compression refrigerating circuit, in which a coolant outlet is provided in a higher position than a coolant inlet, with respect to a vertical direction, such that coolant flows from an underside of the radiator to a top side, as a result of which an improvement in the cooling efficiency of the coolant is promised. Even a radiator of this type, however, still leaves much to be desired in terms of coolant efficiency.